Chimera: a high-speed three-color photometer for satellite characterization

摘要

High-speed optical photometers have been used for decades to characterize man-made satellites and space debris in Earth orbit. In the 1970s and 1980s, these instruments were typically based on photomultiplier tubes (PMT) and provided single-color, or in some cases simultaneous multicolor, photometric data with high time resolution. The original GEODSS PMT photometers were designed to collect photometry on deep space satellites at rates up to 1 kHz. CCDs have since displaced the use of PMTs in photometers in the astronomical community and the GEODSS system. CCDs offer higher quantum efficiency and two-dimensional imaging arrays, but at a lower speed than PMTs. The latest developments and introductions of commercially available Electron-Multiplying CCD (EMCCD) imagers is driving a renaissance in this field with several new instruments in development. Chimera is a high-speed photometer with simultaneous three-color photometry in the Sloan r' (562-695 nm). i' (695-844). and z' (826-920 nm) bands. The optical design provides well-corrected fields of view of 9.7 arcmin in the z' band and 6.0 arcmin in r' and i' bands on the Steward Observatory 61" Kuiper telescope at Mt. Lemmon. The wide field of view facilitates acquisition and tracking of rapidly moving satellites and allows for a variety of photometric calibration methods. The optical design uses a wide-field collimator, two dichroic beam splitters, and three re-imagers. Chimera utilizes three Princeton Instruments Pro-EM HS cameras, which provide data at rates up to 228 Hz in full frame mode. Rates over 1000 Hz are possible by defining photometric regions of interest (ROIs). A highly-modified version of Michael Mommert's photometric pipeline (PP), originally developed for near-Earth asteroid photometry, is used for data processing. A real time graphical user interface is under development to allow real-time data quality assessment and period determination during data collections. In space surveillance, the optical sig